Disengagement from services is a major public health problem for individuals with first-episode psychosis (FEP) as up to 40% of individuals prematurely terminate early care. Individuals with FEP are consequently at increased risk of persistent symptomatic and functional impairment and poor long-term outcomes. Engagement can be improved by (1) identifying pragmatic and effective evidence-based interventions, (2) pinpointing the mechanisms through which change in engagement is achieved, and (3) enhancing the literature on engagement, such as by developing a nuanced and dynamic conceptualization of engagement to guide future research. In the U.S., effective interventions for engagement are particularly needed for community mental health services, which deliver most mental health care and encounter major engagement issues, and for hard- to-reach communities, such as those comprised by Latinos. Research conducted with individuals with psychosis has shown that Behavioral Activation (BA), designed for the treatment of depression, may effectively target engagement and also symptomatic and functional outcomes. This study will develop 12-session BA for FEP and compare it to treatment-as-usual over six months with a sample of 58 (29 per condition) Latinos and their family caregivers in a longitudinal randomized controlled trial. Dyads will also participate in comparable family support groups delivered separately by condition. To examine mechanisms of change, the association between intervention mediators and engagement will be examined to determine whether changes in mediators precede changes in engagement over time. Using mixed-methods, the relationship between local/cultural factors and engagement will be explored. Qualitative methods will be used to explore how local/cultural factors impact engagement for future quantitative analysis, how specific characteristics of robust predictors (e.g., family support) influence engagement, discover other critical influences, consider BA specific factors, and generate a model of engagement in FEP care with attention to stages of development, illness, and treatment. The project provides training in service engagement and intervention for FEP, developing and applying BA for FEP, addressing engagement during FEP in hard-to-reach communities with cultural responsivity, and relevant research methods with primary mentor, Alex Kopelowicz, M.D, co-mentors Steven R. Lopez, Ph.D., Lisa B. Dixon, M.D., M.P.H., and Sona Dimidjian, Ph.D., and consultants Hilary Mairs, Ph.D., Anahi Collado, Ph.D., Mark Lai, Ph.D., Jodie Ullman, Ph.D., Lawrence Palinkas, Ph.D., and Ethel Nicdao, Ph.D. Activities will be sustained through regular communication with and between trainers and resources at California State University San Bernardino, University of Southern California, and relevant institutions/sites. Training supports Dr. Santos?s long-term goal of advancing the field of service engagement for persons with FEP from hard-to- reach communities. The project will enhance the FEP engagement and intervention field and supports the NIMH?s goals of improving engagement and maximizing recovery for persons with early psychotic illness.